Messages in this thread | | | Date | Tue, 14 Jan 2003 17:35:45 -0500 | From | Brian Kelly <> | Subject | How to setup a buffer_head in a driver |
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Hi, I'm writing a device driver that among other things needs to write data, manufactured by the driver itself, to a block device.
I have this data in block sized kmalloc()'d chunks. So what I'm doing is allocating a struct buffer_head, initialising it, fill out it's various fields and send it to generic_make_request(). Something like the following [inspired by looking at various drivers like loop and ram]:
do { if((bh = kmem_cache_alloc(bh_cachep, SLAB_NOIO)) != NULL){ break; } run_task_queue(&tq_disk); schedule_timeout(HZ); } while (1);
memset(bh, 0, sizeof(*bh));
bh->b_size = size; bh->b_dev = dev; bh->b_rdev = dev; bh->b_data = data; init_waitqueue_head(&bh->b_wait); bh->b_rsector = sect; bh->b_end_io = write_done; bh->b_private = NULL; generic_make_request(WRITE, bh);
Now this causes a panic in ll_rw_blk.c because the b_state isn't set correctly. I experimented with this a little but decided I needed some proper direction on this whole endeavour.
Soooo, what do I really need to do? What's the correct way to do what I want to do or could someone point me at an existing driver that does this sort of thing.
Thanks,
Brian -- bkelly@sulaco.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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